There exist a variety of devices for controlled release of specific substances such as drugs in the body (see, for example, U.S. Patent Application Publications Nos. 20070241042; 20070239107; 20070237741; 20070225634; 20070218125; 20070218083; 20070213659; 20070212416; 20070207200; 20070196433; 20070193894; 20070184112; 20070174128; 20070173776; 20070154522; 20070149954; 20070128279; 20070110807; 20070106281; 20070106277-20070106266; 20070088267; 20070050010; 20060285912; 20060210604; 20060198892; 20060182738; 20060178655; 20060124129; 20060116422; 20060115785; 20060034913; 20060030837; 20060029653; 20060020253; 20060003008; 20050273049; 20050249798; 20050222627; 20050205083; 20050158246; 20050149000; 20050148847; 20050147678; 20050107870; 20050070996; 20050058701; 20040253304; 20040219186; 20040204750; 20040180088; 20040161382; 20040138733; 20040086562; 20040077513; 20040032187; 20040024382; 20040022853; 20040005359; 20030216683; 20030172924; 20030133979; 20030120339; 20030036746; 20020183682; 20020168410; 20020123678; 20010020147; and 20010002262).
There may be times when it is desirable to continuously administer a substance such as drug to a patient over a long period of time. Further, there may be times when it is desirable to deliver a substance at specified time intervals over a period of time. Most prior art devices are not capable of remaining in the body (e.g., in a cavity or orifice) long enough to provide continuous release over extended periods of time. Further, most devices lack a precise feedback control mechanism to achieve completely controlled release of a substance from the device.
Consequently, the need has arisen for a substance delivery device that allows controlled delivery of specific substances in a given orifice or cavity in the body in situ to address some of the problems encountered in the prior art.